EOS 5D Mark III multiple exposure mode
EOS 5D Mark III includes a multiple exposure mode that makes in-camera composite images simple to do, and very importantly it allows each of the component images to be saved as a RAW image as well as the final composite.
Taking a simple subject and lighting them with two flashes, one on the left and one on the right. The flashes were set to be evenly balanced regardless of the location of my model. Simply put the Speedlite on the left was in group A and the one on the right in Group B, the transmitter on the camera set to ratio A:B groups evenly.
So the result is a few images and the camera then creates the composite result – even the composite is saved as a RAW file. It is necessary to chose the blending method in the camera, there are four options available; Additive, Average, Bright and Dark. Really helpful is to use Live View mode, since then the camera LCD shows the composite as each image is taken. This makes it really simple to align each of the shots with the model separated from his position in previous pictures.
The room was only light with the Speedlites, but as the top image shows there was a lot of light in the room as a result of the five separate exposures. All the light adds up, each of the individual frames is much darker. Below you can see the set of images that were taken for the composite. Below you can see each of the individual frames (click on them for a little larger view).
Keep all the individual RAW files to use in DPP
One benefit of having all the individual RAW images from a composite is that if you choose the wrong blend mode in the camera menu then it is possible to use the Compositing Tool in Digital Photo Professional (DPP). DPP is the free RAW processing software that is supplied with each and every EOS camera. So it’s possible to redo the composite with a better blending later.
DPP has five blending modes available the Compositing Tool; Add, Average, Weighted, Lighten and Darken. Four of these blend modes match the ones available in camera, weighted is additional since you can change the amount of blending with a slider. Also it is possible to have different blending for each layer you add to the composite. You can even move each of the composite layers relative to each other. There is more information about composites on page 2 of my article on Canon Professional Network (CPN).
I used the Lighten blend mode for this version using 3 of the source images from the original image. This helped preserve the darkness of the background from each image rather than add all the brightness together and produce the brighter than desired background of the in-camera Additive setting chosen when the picture was taken.